With recent developments in the integrated circuit technology, it has become possible to build synthesizers or computers which can process sound samples rapidly and efficiently. Indeed, in some music production and performance contexts, such as pop music concerts and recordings, it has become convenient and inexpensive to use synthesizers or electronic instruments instead of live performers. The "Clavinova" produced by Yamaha, MIDI guitars, and synthesizers produced by Kurzweil and Yamaha, are examples of popular electronic instruments.
The ultimate goal in the design of these instruments is to obtain sounds as close as possible to the synthesized instrument, for the complete pitch range, while maintaining low cost and complexity. To achieve this goal, sound perception and psycho acoustics must be well understood, to determine which components of the sound are significant to the human ear, in order to simplify synthesis models without sacrificing sound quality.
The current state of the art synthesizers, in general, use a combination of wavetable synthesis, FM synthesis and additive synthesis methods. There are some very new models which also incorporate physical modeling synthesis. In wavetable synthesis, some portion or all of the sound of the acoustic instrument note is digitally recorded. Then the recorded sound data is digitally processed to obtain notes with various amplitudes, durations, pitches and other expressive parameters specific to that instrument. In FM synthesis, no pre-recorded sound data is used; rather, pairs of oscillators produce frequency and amplitude modulated sine waves which are added after being properly enveloped and weighted. In additive synthesis, the frequency components of the sound are separately produced, enveloped and added. Pure additive synthesis is not commercially viable since the number of components which have to be used for a realistic sound is very high, especially for the synthesis of transient and non-linear portions. Finally, in physical modeling synthesis, the equations which govern the instrument's wave propagation, are solved numerically, with the results producing the sound samples.
Different ones of these methods, or combinations of these methods, have been found to be successful in the synthesis of different specific instruments. In particular, FM and wavetable synthesis methods are very successfully applied to pianos, most percussive instruments and some wind instruments in some pitch ranges. Physical modeling synthesis, on the other hand, is very powerful in the synthesis of sounds produced by non-linear effects, which are particularly significant in bowed string instruments or all wind instruments. However, physical modeling synthesis models are very new and difficult to implement, and as a result are not yet commercially viable.